2′-Deoxynucleosides and their analogues are therapeutically important agents. For example, 2′-deoxy-2,2′-difluorocytidine hydrochloride can be used to treat viral infection and cancer (see, e.g., U.S. Pat. Nos. 4,526,988 and 4,808,614).
In general, 2′-deoxynucleosides each have more than one chiral center and can occur as multiple stereoisomers. Not all stereoisomers are therapeutically active. Several stereoselective synthetic routes for 2-deoxy-β-nucleosides have been developed. However, none of them are satisfactory. For example, U.S. Pat. No. 5,648,473 describes a synthetic method that produces β anomer-enriched 2-deoxy-β-nucleoside from α-anomer of furanose. This method is economically ineffective, as it requires an anomerically pure or enriched starting material.
There is a need to develop a more effective route for stereoselectively synthesizing 2′-deoxynucleosides.